mobile behaviour – amount of displayed columns

hello dear team,

mobile behaviour – amount of displayed columns

is there a possibility to change the breakpoint for the amount of displayed columns?
i used site origin features on the starting page: http://thepoetryproject.de.
regulary the grid cell shows
> 521 px 3 columns
1024 px 3 columns
< 1024 px 1 cloumnn (max-width)

i already changed Device width in page builder settings, both tablet and mobile, and deacivated tablet layout, but it didn’t have any effect on this.

is there any way, that i didn’t mention?
or could you help me with a css-code, please?